The invention relates to pigment preparations containing nanometer-size inorganic pigments, processes for their preparation, and their use as ink for ink-jet printing.
The colorants used for ink-jet printing include both water-soluble dyestuffs and organic coloring pigments and carbon blacks. In general, organic dyestuffs produce strong prints of high brilliance but often exhibit poorer lightfastness compared with coloring pigments. Organic pigments often have the disadvantage of showing a lack in brilliance and/or transparency, and their lightfastness is still insufficient for a variety of applications, for example, for outside applications. Especially in the area of black ink-jet colorants, both organic dyestuffs and inorganic coloring pigments and carbon blacks do not yet meet the desired properties in terms of high optical density and lightfastness.
Thus, for example, Japanese Patent 62/179,579 describes pigment preparations containing titanium nitride in which the TiN used, as disclosed by the manufacturer, has an average particle diameter greater than 0.7 .mu.m.
The object of the present invention is to provide aqueous pigment preparations for use as ink-jet inks which can be used for producing prints having improved lightfastness while exhibiting high optical density.